The present invention relates to a navigation apparatus.
Among navigation apparatus on the market is one, for example, disclosed in Laid-open Japanese Patent (KOKAI) No. 7-63570/1995, in which map-matching is performed to display where on a road the user is. That is, a check is made based on the present position determined by the GPS to determine whether a present position is on a road in a map, the road lying within a range of measurement error and being matched to the track of movement of a navigation apparatus or a vehicle on which the navigation apparatus is carried. Thus, if the present position found by the GPS is in fact on the road, the present position is displayed on the road.
Laid-open Japanese Patent (KOKAI) No. 8-35850/1996 has proposed displaying characters representative of the name of a road that coincides with a position determined by the GPS. This is useful because displaying character information allows the user to easily or quickly know where he is.
One of the problems associated with conventional navigation apparatus is that the name of a road may not be displayed, i.e., no character information on the present position is displayed. This occurs if a road on the map does not exist within a range of error in which a track of movement of the navigation apparatus can be determined, or if there is no data describing the name of a road that matches the track movement.
Another problem is associated with a portable navigation apparatus. The portable navigation apparatus can be carried around by the user, and also can be carried on an automobile or a bicycle. Such a navigation apparatus incorporates built-in batteries or is designed to receive electric power from an external power source through, for example, an electric power outlet (e.g., cigar lighter) of an automobile.
Usually, GPS has an error of about 20 m. When a user carries around a portable navigator, the GPS fails to detect the direction in which the user walks, because the apparatus does not move fast enough, i.e., the user does not walk as fast as the GPS can determine the direction of movement of the user with its designed accuracy. As a result, map-matching (effected on the basis of the track of movement of the apparatus) cannot be performed while the walker is walking.
Still another problem is that when the user is walking in an alley, through a park, or in an amusement park, the apparatus may erroneously determine that the user is walking on a nearby road.
An object of the present invention is to solve the aforementioned problems. The present invention provides a navigation apparatus having:
map information reproducing means that can reproduce road map information, road name information, and area information;
position detecting means that detects a present position;
display means that displays road map information and the present position;
controlling means that performs map-matching in which the present position detected by said position detecting means is checked against the road map information;
wherein when the map-matching finds a road on which the present position lies, the controlling means causes the display means to display a name of the road; and
wherein when said map-matching fails to find the road on which the present position lies, the controlling means causes the display means to display the area information in which the present position lies.
The present invention provides a navigation apparatus having:
map information reproducing means that can reproduce road map information, road name information, and area information;
position detecting means that detects a present position;
display means that displays the road map information and the present position;
controlling means that performs map-matching in which the present position detected by said position detecting means is checked against the road map information;
wherein when the map-matching fails to find road name information corresponding to the present position, the controlling means causes the display means to display the area information.
The present invention provides a portable navigation apparatus having:
an internal power supply;
a terminal through which electric power is received from an external power source;
map information reproducing means that reproducing map information;
position detecting means that detects a present position;
display means that displays the present position and road map information;
controlling means that performs map-matching in which the present position detected by said position detecting means is checked against the road map information;
external power supply detecting means that determines whether electric power is being supplied from an external power source;
wherein when said external power supply detecting means determines that electric power is being supplied from the external power source, said controlling means performs the map-matching; and
wherein when said external power supply detecting means determines that electric power is not supplied from the external power source, said controlling means does not perform the map-matching.